Title :
Magnetic Fluctuations in Individual Superparamagnetic Particles
Author :
Piotrowski, Stephan K. ; Matty, Michael F. ; Majetich, Sara A.
Author_Institution :
Phys. Dept., Carnegie Mellon Univ., Pittsburgh, PA, USA
Abstract :
Fluctuations of the magnetic moment direction of single Fe3O4 nanoparticles were measured by conductive atomic force microscopy. Superparamagnetic nanoparticles were deposited on an Fe-Pt thin film, and the current through the film and individual particles was detected as a function of time. Due to magnetoresistance in the particle-film system, changes in the particle moment direction lead to different current levels. The effect of magnetic fields between -69 and 153 Oe on the characteristic current levels was used to determine the effective anisotropy of the particle. Magnetoresistance values of 45% were observed.
Keywords :
atomic force microscopy; iron; iron compounds; magnetic anisotropy; magnetic moments; magnetic particles; magnetic thin films; magnetoresistance; metallic thin films; nanomagnetics; nanoparticles; platinum; superparamagnetism; Fe-Pt; Fe3O4-Fe-Pt; conductive atomic force microscopy; current level; magnetic field; magnetic fluctuation; magnetic moment; magnetoresistance; nanoparticles; particle moment direction; particle-film system; superparamagnetic nanoparticles; thin film; Magnetic separation; Magnetic tunneling; Nanoparticles; Perpendicular magnetic anisotropy; Probes; Saturation magnetization; Conductive AFM (C-AFM); magnetite; magnetoresistance; nanoparticle;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2014.2321327
